TL:DR I don't have enough information to give you the exact answer your looking for but I will at least try and remind your colonists that other options are available
agriculture is complex, the fact that we've been doing it for 12000 years or so and still haven't figured it all out is testament to that, it depends on the mineral and microbial composition of the soil. The duration, intensity and colour of light can all effect yield. It depends on atmosphere and the specifics of that one plant your looking at and all of these issues are interconnected and not necessarily isolatable variables. All of these factors are going to be radically different on an alein world making this question really tough to answer if not impossible
Option 0: just bring all the plants!
Seeds don't take up all that much room or mass budget, and you should always prepare for the unpredicted, having as many different and varied species of plants as possible will give your colonists the best chance of survival, as well as the most varied pallete on this new frontier (very useful for not going insane). More varied crops will also simply be good in the long run for building a diverse robust ecosystem, your trying to build a civilisation here after all and man cannot live of wheat alone.
Option 1: don't grow plants in the open!
there are quite extreme seasons on this planet due to the extra 6.5 degrees of axial tilt, it's apperently a dry waste-land so the open air isn't going to be the best for growing plants while conserving water, The very long day (unless by 24.475 you mean hours) presents a hell of a lot of problems as does the option of contamination with an unknown alien environment, if all your potatoes die because of some stupid alien blight it doesn't really matter that you brought them. Artificial environments are your best bet. These would preferably spend about half their time artificially lit, be rich in carbon dioxide and have a large water reservoir/heat storage device directly underneath. This way your Norwegians can grow plants in an ideal known environment before moving on to the alien environment after a great deal of study to select the right plant. Remember that in order to have even got there in the first place you probably have a facility like this aboard your space-ship anyway.
Option 2: alein flora.
So i know you said "don't worry about alien flora or fauna" but presumably their must be some flora or else their isn't a nice oxygen atmosphere for your plants to survive in, if you can find this flora it will probably be ideally adapted to this alien environment and after an intensive breeding program, a bit of genetic engineering or perhaps cross-breeding with earth plants (though that last option seems unlikely).
Option 3: double cropping! (but actually only single cropping)
there are plants that we can "double crop" that is to say get two crops out of in a single year, needless to say any of those plants could be single cropped in a year half as long. There are crops that we still can double crop in arid environments so any of these should be suitable, though again more variety is always better. If sufficient irrigation can be set up then any double cropped crop might do, but it seems unlikely you'll be able to set up heavy irrigation systems so soon after landing.
Examples of double-cropped crops are very numerous but corn & potatoes are both reasonably not-bad bets.
Option 4: assorted weeds & grasses (and some frozen cattle).
Grass is very fast spreading, has a short generational gap (good for evolving naturally to it's new climate) and can thrive in arid climates. While it's not edible to humans without significant processing it is edible to humanity's favourite food. If your colonists have access to cryostatis they could drop grass seeds, then animals and then a few decades later land to find a tranquil African-Savannah-esque landscape waiting to be hunted for food.
